A. Field of the Invention
This invention relates generally to the field of devices used to measure and display bio-potential signals generated by the body. More particularly, the invention relates to a plurality of wireless, remotely programmable electrode transceiver assemblies that are each coupled to a conventional patch electrode, and an associated base unit. The base unit obtains a patient's electrocardiogram (ECG) or other bio-potential signal from the wireless transceivers and supplies the signal to a monitor unit for display. The display may be a standard ECG monitor.
B. Statement of Related Art
Conventional ECG apparatus for hospital bedside monitoring typically requires up to ten wired electrodes. Each electrode is attached to the body of the patient, and has a wire, several feet or more in length, leading to an ECG monitor. Such electrodes are used to detect heart signals from the patient and convert them into a multiple-lead ECG evaluation.
The lengthy wired electrodes of conventional ECG apparatus obstruct the patient and limit the patient's freedom of movement. They are also cumbersome for the physician or assisting nurse. Telemetry systems for wireless ECG monitoring for patients in hospitals currently exist. These systems are more expensive, intended for greater range (higher power), and do not totally eliminate the physical electrode wires attached to the patient. Instead of being connected to the monitor, the electrodes are each wired to a single transmitter box that is worn by the patient. Some telemetry systems also may not handle a 12 lead ECG (10 wires) because of the wiring that is required between the electrodes and the transmitter box. For example, the Spacelabs Ultraview Modular Digital Telemetry system can only handle a maximum of four leads (5 wires).
Wireless medical monitoring and diagnosis systems have been proposed in the prior art. U.S. Pat. No. 5,862,803 to Besson et al. describes a wireless electrode/sensor patch system with sensor, controller and transceiver electronics contained in an electrode patch assembly. U.S. Pat. Nos. 5,307,818, 5,168,814 and 4,981,141, all issued to Segalowitz, describe a wireless electrode system for ECG monitoring. The Besson et al. and Segalowitz patents are incorporated by reference herein. The Segalowitz patents describe a single piece electrode patch with built-in microchips for wireless one way communication, and a snap on electronic-assembly that fastens to a disposable electrode patch. However, the electrode patch is a special two-conductor type that is not conventional. The electrode assemblies are either transmit only or receive only (not both). A reference signal (generated from a Wilson network) is transmitted from the base unit to only the Right Leg electrode patch, which is receive only. Electrodes can only be programmed via manual switches on the electrode casing, not over-the-air from the base unit. For the multiple electrode embodiment, the base unit contains multiple receivers and antennas which imply multiple transmit frequencies are required for the system and over-the-air signaling (thus making the base unit more costly to implement). There is no mention of error correction or detection capability in the electrodes or base unit.
In another embodiment of the Segalowitz '818 patent, there is discussion of a single strip assembly which contains all of the electrodes required for 12-lead ECG monitoring with microchip circuitry contained in the strip assembly (not in the individual electrode patches). In this configuration, the ECG signals from each electrode are multiplexed and transmitted from a single transmitter (contained in the strip assembly) via time multiplexing on a single digitally encoded frequency channel. However, no time multiplexing on a single frequency channel is discussed for their multiple transmit electrode embodiment, as discussed in the present invention.
The present invention is not intended to replace existing telemetry systems, but rather to provide a more convenient and cost effective solution for low power wireless ECG monitoring, in a hospital room environment, without having to replace the hospital's existing ECG bedside monitoring equipment. Furthermore, the present invention provides for programmable features by which a base unit can remotely program multiple wireless transceivers. This provides greater flexibility and customization of a wireless ECG acquisition system. As such, it is believed to be an improvement to the systems proposed by Besson et al. and Segalowitz.